MOLECULAR CONSTANTS FOR THE $\nu_{3}$ FUNDAMENTAL OF $SF_{6}$

$^{1}$ C. W. Holt, M. C. L. Gerry, and I. Ozier, Can. J. Phys. 53, 1791 (1975). R. M. Lees has been on leave of absence from Department of Physics, University of New Brunswick, Fredericton, New Brunswick, Canada.Author Institution: Los Alamos Scientific Laboratory, University of CaliforniaWe have studied the $\nu_{3}$ = 1 fundamental of $SF_{6}$ through the very high resolution (better than 100 kHz laser diode) spectra of $Hinkley.^{1}$ The experimental data used In this analysis consisted of fifty-two non-blended lines lying in the regions of R(30), P(33), and P(58) of $SF_{6}$. [These transitions are all within $\pm$ 1.5 GHz of the $CO_{2}$ P(14), P(18), and P(20) laser $lines.^{2}$] Having assigned all relevant transitions according to their respective J-values and octahedral notations, a least squares fit of theory to experiment was carried out. Four scalar and three tensor parameters were thereby obtained. In the notation of Moret-$Bailly^{3,4}$ we have found (in $cm^{-1}$) \begin{eqnarray*} m &=& 947.9675 \pm 0.0011\\ n &=& 0.055688 \pm 0.000016\\ P &=& (-1.518 \pm 0.012) \times 10^{-4}\\ q &=& (1.75 \pm 0.20) \times 10^{-7} \hbox{ for the sealers, and}\\ g &=& (-2.460 \pm 0.007) \times 10^{-5}\\ h& =& (8.4 \pm 2.0) \times 10^{-9}\\ \hbox{and } k &=& (-2.0 \pm 0.5) \times 10^{-10}\end{eqnarray*} as tensor parameters. Errors given are standard deviations, and the overall fit was to within 8.8 MHz. It was necessary to Include tensor matrix elements connecting appropriate states across the P, Q, and R branches of the fundamental